The present invention relates generally to an electrical power strip, and more particularly, to an electrical power strip connectable to a 12 or 24 volt DC electrical power system, such as a vehicular battery or a vehicular alternator, for making power available to vehicle accessory items.
Some vehicle accessory items, such as hand-held automobile vacuum cleaners, electrical shavers, and the like, are intended for operation using relatively low electric current (i.e., 2-6 amps). These low current vehicle accessory items typically employ a vehicle accessory plug compatible with a plug-receiving socket (i.e. a cigarette lighter socket) in a vehicle. In comparison, other vehicle accessory items, such as hair dryers, coffee makers, and the like, require relatively high electric current levels (i.e. 8-20 amps) to operate. These high current vehicle accessory items suffer from a problem of heat build-up in the electrical connector at electric current levels of 10-15 amps or more, if a vehicle accessory plug is used. When a vehicle accessory plug is plugged into a plug-receiving socket (i.e. a cigarette lighter socket) in a vehicle, a contact area is formed between the positive connector of the plug and the positive connector of the socket. Since the contact area located at the tip of the vehicle accessory plug is relatively small, the electric current density in the contact area will be relatively great with high current loads. The greater the current density, the more heat is generated in the contact area. As a result, the problem of heat build-up seriously impairs the operating characteristics of these high current vehicle accessory items and significantly reduces their life of use. The same phenomenon may be true with the negative contact, depending on the surface area thereof.
The present invention overcomes such shortcomings of the prior art by providing an electrical power strip with relatively high current capacity and reduced current density to avoid the problem of heat build-up. In addition, the present invention provides a blocking mechanism inside a polarized receptacle of the electrical power strip for preventing improper connection to the polarized receptacle as well as for enabling proper connection to the polarized receptacle by a specially manufactured polarized plug of the vehicle accessory item. Preferably, the physical appearance of the plug prongs and corresponding receptacle slots is representative of the respective polarity, with a first prong having a cross-sectional shape in a general form of a xe2x80x9c+xe2x80x9d (plus) sign, a second prong having a cross-sectional shape in a general form of a xe2x80x9cxe2x88x92xe2x80x9d (negative) sign, a first slot having a generally xe2x80x9c+xe2x80x9d-shaped aperture, and a second slot having a generally xe2x80x9cxe2x88x92xe2x80x9d-shaped aperture.